sql - JSON without array wrapper on lower levels

Question

All I try to get is a simple SQL statement to build:

 {"status":{"code":404,"message":"Not found"},"otherthing":20}

If I set as :

DECLARE @ReturnJSON nvarchar(max)

SET @ReturnJSON = (
    SELECT ( 
        SELECT 404 as [code]
              ,'Not found' as [message] 
               FOR JSON PATH ) as [status]
       , 20 as [otherthing]
   FOR JSON PATH, WITHOUT_ARRAY_WRAPPER) ;

SELECT @ReturnJSON 

I get the second level under an array wrapper, like this:

{"status":[{"code":404,"message":"Not found"}],"otherthing":20}

But if I add the WITHOUT_ARRAY_WRAPPER on the second level...

DECLARE @ReturnJSON nvarchar(max)

SET @ReturnJSON = (
    SELECT ( 
        SELECT 404 as [code]
              ,'Not found' as [message] 
               FOR JSON PATH, WITHOUT_ARRAY_WRAPPER ) as [status]
       , 20 as [otherthing]
   FOR JSON PATH, WITHOUT_ARRAY_WRAPPER) ;

SELECT @ReturnJSON 

something funny happens:

{"status":"{"code":404,"message":"Not found"}","otherthing":20}

I am missing something, I know, sure, but I can not for-see

Answer 1

I think that Matheno (in the comments) is right: apparently the problem is that FOR JSON escapes your text. To prevent this unwanted escaping of inner JSON you could wrap it with JSON_QUERY():

DECLARE @ReturnJSON nvarchar(max)
DECLARE @innerJSON nvarchar(max)

set @innerJSON =(        SELECT 404 as [code]
              ,'Not found' as [message] 
               FOR JSON PATH, WITHOUT_ARRAY_WRAPPER )

SET @ReturnJSON = (
    SELECT ( 
        JSON_QUERY(@innerJSON)
               ) as [status]
       , 20 as [otherthing]
   FOR JSON PATH, WITHOUT_ARRAY_WRAPPER) ;

SELECT @ReturnJSON 

This outputs:

{"status":{"code":404,"message":"Not found"},"otherthing":20}